title: Scheimpflug corneal power measurements for intraocular lens power calculation in cataract surgery.
abstract: OBJECTIVE
  To compare the keratometric (K) readings from the Pentacam-HR (High Resolution) unit with the automated K values from the IOLMaster keratometer (KIOLM), and to evaluate them in the commonly used intraocular lens (IOL) power calculation formulas for routine cataract surgery.
  
  
  METHODS
  Prospective, comparative observational study.
  
  
  METHODS
  setting: Private practice, Lynwood, California. study population: Fifty cataractous eyes scheduled for surgery between July and August 2012. observation procedure: The K readings from the Pentacam-HR unit taken at the 2-, 3-, 4-, and 5-mm zones and the 2-, 3-, 4-, and 5-mm rings, respectively, from 3 different maps: sagittal corneal front (KF), true net power (KTNP), and total refractive power (KRP) are compared with KIOLM. IOL power calculations were performed with each of the 25 sets of K readings. main outcome measures: The IOL prediction median absolute error (MedAE) obtained with each measurement.
  
  
  RESULTS
  KF averaged 0.03-0.13 diopter (D) higher than KIOLM (P > .05), KTNP averaged 1.16-1.21 D lower than KIOLM (P > .001), and KRP averaged 0.23-0.72 D lower than KIOLM (P > .001), with large variations in the measurements. The MedAE obtained with the different Pentacam K readings ranged from 0.44-0.64 D vs 0.52 D obtained with KIOLM (P > .05). MedAE was lower in all categories when the pupil was 3 mm or smaller.
  
  
  CONCLUSIONS
  The Pentacam KF values were the closest to KIOLM and the KF readings from the 2-mm ring yielded the best results for IOL power calculation.
authors.affiliation: Shammas Eye Medical Center, Lynwood, California.
authors.forename: Elie
authors.initials: E
authors.lastname: Saad
authors.affiliation: Shammas Eye Medical Center, Lynwood, California.
authors.forename: Maya C
authors.initials: MC
authors.lastname: Shammas
authors.affiliation: University of Southern California, The Keck School of Medicine, Lynwood, California; Shammas Eye Medical Center, Lynwood, California. Electronic address: Jshammas@shammaseye.com.
authors.forename: H John
authors.initials: HJ
authors.lastname: Shammas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058452:Axial Length, Eye; D001699:Biometry / Q000295:instrumentation; D002386:Cataract / Q000150:complications; D003315:Cornea / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D007368:Interferometry; D007910:Lenses, Intraocular; D008027:Light; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D018918:Phacoemulsification; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*